# Publications

2000
McConnell ML, Bennett K, Bloemen H, Collmar W, Hermsen W, Kuiper L, Phlips B, Ryan JM, Schoenfelder V, Steinle H, et al. The Spectral Variability of Cygnus X-1 at MeV Energies . American Institute of Physics Conference Proceedings [Internet]. 2000;510 :114. Publisher's VersionAbstract

In previous work, we have used data from the first three years of the CGRO mission to assemble a broad-band \$\gamma\$-ray spectrum of the galactic black hole candidate Cygnus X-1. Contemporaneous data from the COMPTEL, OSSE and BATSE experiments on CGRO were selected on the basis of the hard X-ray flux (45–140 keV) as measured by BATSE. This provided a spectrum of Cygnus X-1 in its canonical low X-ray state (as measured at energies below 10 keV), covering the energy range from 50 keV to 5 MeV. Here we report on a comparison of this spectrum to a COMPTEL-OSSE spectrum collected during a high X-ray state of Cygnus X-1 (May, 1996). These data provide evidence for significant spectral variability at energies above 1 MeV. In particular, whereas the hard X-ray flux ıt decreases during the high X-ray state, the flux at energies above 1 MeV ıt increases, resulting in a significantly harder high energy spectrum. This behavior is consistent with the general picture of galactic black hole candidates having two distinct spectral forms at soft \$\gamma\$-ray energies. These data extend this picture, for the first time, to energies above 1 MeV.

1999
Morris DJ, McConnell ML, Ryan JM, Diehl R, Oberlack UG, Schönfelder V, Varendorff M, Weidenspointer G, DEBOER H, Bennett K. Activation in the COMPTEL Double-Scattering Gamma-Ray Telescope, in High Energy Radiation Background in Space. ; 1999 :26–26.
Ryan JM, Kappadath S, McConnell M, Morris D, Schönfelder V, Varendorff M, Weidenspointer G, Hermsen W, Bennett K. The Prompt Cosmic-Ray-Induced Background in the Orbiting Compton Telescope COMPTEL, in High Energy Radiation Background in Space. ; 1999 :13–13.
Wunderer CB, Holslin D, Macri JR, McConnell M, Ryan JM. SONTRAC-A Low Background, Large Area Solar Neutron Spectrometer, in High Energy Radiation Background in Space. ; 1999 :73–73.
Mallozzi RS, Kippen RM, Pendleton GN, Paciesas W, Richardson GA, Phengchamnan S, Karr G, Wallace DB, Fishman GJ, Parnell TA, et al. Beam test results for the FiberGLAST instrument, in SPIE Proceedings. ; 1999. Publisher's VersionAbstract
The FiberGLAST scintillating fiber telescope is a large-area instrument concept for NASA’s GLAST program. The detector is designed for high-energy gamma-ray astronomy, and uses plastic scintillating fibers to combine a photon pair tracking telescope and a calorimeter into a single instrument. A small prototype detector has been tested with high energy photons at the Thomas Jefferson National Accelerator Facility. We report on the result of this beam test, including scintillating fiber performance, photon track reconstruction, angular resolution, and detector efficiency.
Rielage KR, Arisaka K, Atac M, Binns WR, Buckley JH, Cherry ML, Christl MJ, Cline DB, Dowkontt PF, Epstein JW, et al. Development and testing of a fiber/multianode photomultiplier system for use on FiberGLAST, in Hard X-Ray, Gamma-Ray, and Neutron Detector Physics. Vol 3768. ; 1999 :156–165.
Tousignant O, Hamel LA, Dufour PC, Joly F, Macri JR, McConnell ML, Ryan J, Jordanov VT. Energy and position resolution of a CdZnTe gamma-ray detector with orthogonal coplanar anodes, in SPIE Proceedings. ; 1999. Publisher's VersionAbstract
We report on the simulation, construction and performance of prototype CZT imaging detectors employing orthogonal coplanar anodes. These detectors employ a novel electrode geometry with non-collecting anode strips in 1D and collecting anode pixels, interconnected in rows, in the orthogonal dimensions. These detectors retain the spectroscopic and detection efficiency advantages of single carried charge sensing devices as well as the principal advantage of conventional strip detectors with orthogonal anode and cathode strips, i.e. an N X N array of imagin pixels are realized with only 2N electronic channels. Charge signals induced on the various electrodes of a prototype detector with 8 X 8 unit cells are in good agreement with the simulations. The position resolution is about 1 mm in the direction perpendicular to the pixel lines while it is of the order of 100 micrometers in the other direction. Energy resolutions of 0.9 percent at 662 keV, 2.6 percent at 122 keV and 5.7 percent at 60 keV have been obtained at room temperature.
Pendleton GN, Binns WR, Israel MW, Hink PL, Cherry ML, Paciesas W, Kippen RM, Mallozzi RS, Parnell TA, Fishman GJ, et al. FiberGLAST: a scintillating fiber approach to the GLAST mission, in SPIE Proceedings. ; 1999. Publisher's VersionAbstract
FiberGLAST is a scintillating fiber gamma-ray detector designed for the GLAST mission. The system described below provides superior effective area and field of view for modest cost and risk. An overview of the FiberGLAST instrument is presented, as well as a more detailed description of the principle elements of the primary detector volume. The triggering and readout electronics are described, and Monte Carlo Simulations of the instrument performance are presented.
McConnell ML, Macri JR, McClish M, Ryalls J. Recent laboratory tests of a hard x-ray solar flare polarimeter, in SPIE Proceedings. ; 1999. Publisher's VersionAbstract
We report on the development of a Compton scatter polarimeter for measuring the linear polarization of hard X-rays (50 - 300 keV) from solar flares. Such measurements would be useful for studying the directivity (or beaming) of the electrons that are accelerated in solar flares. We initially used a simple prototype polarimeter to successfully demonstrate the reliability of our Monte Carlo simulation code and to demonstrate our ability to generate a polarized photon source in the lab. We have recently fabricated a science model based on a modular design concept that places a self-contained polarimeter module on the front-end of a 5-inch position- sensitive PMT (PSPMT). The PSPMT is used to determine the Compton interaction location within an annular array of small plastic scintillator elements. Some of the photons that scatter within the plastic scintillator array are subsequently absorbed by a small centrally-located array of CsI(Tl) crystals that is read out by an independent multi-anode PMT. The independence of the two PMT readout schemes provides appropriate timing information for event triggering. We are currently testing this new polarimeter design in the laboratory to evaluate the performance characteristics of this design. Here we present the initial results from these laboratory tests. The modular nature of this design lends itself toward its accommodation on a balloon or spacecraft platform. A small array of such modules can provide a minimum detectable polarization (MDP) of less than 1% in the integrated 50 - 300 keV energy range for X-class solar flares.
McConnell ML, Ryan JM, Collmar W, Schonfelder V, Steinle H, Strong AW, Bloemen H, Hermsen W, Kuiper L, Bennett K, et al. A Broad Band Gamma-Ray Spectrum of Cygnus X-1, in AAS/High Energy Astrophysics Division #4. Vol 31. ; 1999 :731–731.
Cherry ML, Altice PP, Band DL, Buckley JH, Guzik TG, Hink PL, Kappadath SC, Macri JR, Matteson JL, McConnell ML, et al. Coded-aperture x-ray/gamma-ray telescope for arc-minute localization of gamma-ray bursts, in EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy X. Vol 3765. ; 1999 :539–550.
Kappadath SC, McConnell M, Ryan J, Bennett K, Winkler C, Bloemen H, Hermsen W, Schoenfelder V, Varendorff M, Weidenspointner G. COMPTEL Measurements of the Cosmic Diffuse Gamma-Ray Spectrum from 800 keV to 30 MeV, in AAS/High Energy Astrophysics Division #4. Vol 31. ; 1999 :737–737.
Ryan JM, Macri J, McConnell ML. Development of SONTRAC, a Solar Neutron Tracking Device, in American Astronomical Society Meeting Abstracts #194. Vol 31. ; 1999 :959–959.
Young CA, Connors A, McConnell M, Rank G, Ryan JM, Sulieiman R, Schoenfelder V. Energetic Proton Spectra in the 11 June 1991 and 24 October 1991 Solar Flares, in American Astronomical Society Meeting Abstracts #194. Vol 31. ; 1999 :859–859.
Young CA, Connors A, McConnell M, Ryan JM, Williams OR, Winkler C, Bennett K, Hermsen W, Kuiper L, Collmar W, et al. High Energy (MeV) Characteristics of GRB 990123 as Measured by CGRO-COMPTEL, in AAS/High Energy Astrophysics Division #4. Vol 31. ; 1999 :711–711.
McConnell ML, Macri J, McClish M, Ryan JM. Laboratory Testing of a Hard X-Ray Solar Flare Polarimeter, in American Astronomical Society Meeting Abstracts #194. Vol 31. ; 1999 :959–959.
Altice PP, Cherry ML, Guzik TG, Kappadath SC, Stacy JG, Macri J, McConnell ML, Ryan JM, Band DL, Matteson JL, et al. Minute-of-Arc Resolution Gamma ray Imaging Experiment – MARGIE, in AAS/High Energy Astrophysics Division #4. Vol 31. ; 1999 :728–728.
Barrett P, McConnell M, Drake S, Lim J, Ferrario L, Vennes S. Radio and Optical Observations of RE J0317-853: a Suspected 2.2 MeV Gamma-Ray Source, in AAS/High Energy Astrophysics Division #4. Vol 31. ; 1999 :736–736.
Ryan J, Li W, Macri JR, McConnell ML, Castaneda C, Romero JL. Recent progress in the development of a solar neutron tracking device (SONTRAC), in SPIE Proceedings. ; 1999. Publisher's VersionAbstract
We report the results of recent calibration data analysis of a prototype scintillating fiber tracking detector system designed to perform imaging, spectroscopy and particle identification on 20 to 250 MeV neutrons and protons. We present the neutron imaging concept and briefly review the detection principle and the prototype description. The prototype detector system records ionization track data on an event-by-event basis allowing event selection criteria to be used in the off-line analysis. Images of acrylic phantoms from the analysis of recent proton beam calibrations are presented as demonstrations of the particle identification, imaging and energy measurement capabilities. The measured position resolution is \textless 500 micrometers . The measured energy resolution is 14.2 percent at 35 MeV. The detection techniques employed can be applied to measurements in a variety of disciplines including solar and atmospheric physics, radiation therapy and nuclear materials monitoring. These applications are discussed briefly as are alternative detector configurations and future development plans.
Diehl R, Oberlack U, Pluschke S, Knodlseder J, Bloemen H, Hartmann D, Hermsen W, McConnell M, Schonfelder V, Strong AW, et al. 1.8 MeV gamma-rays from the Vela region. ASTROPHYSICAL LETTERS & COMMUNICATIONS [Internet]. 1999;38 :357–362. Publisher's Version